Sheaths for thermometers or other probes are well-known and in commercial use, being used to protect against any cross-infection from one patient to another by the reuse of incompletely sterilized thermometers or the like. Examples of such sheaths are illustrated in the pending patent applications of Harry Bala, specifically U.S. application Ser. No. 205,316, filed Jun. 10, 1988 and entitled Sheath for Probe With Improved Seal Arrangement, now U.S. Pat. No. 4,823,949; and U.S. application Ser. No. 212,969, filed Jun. 29, 1988 and entitled Sheath for Thermometer and the Like, now U.S. Pat. No. 4,846,344.
The probe sheaths of the prior art are typically made in flattened form out of a pair of flat sides, which are peripherally sealed together with the probe sheath being enclosed in a package. This of course requires the use of plastic sheeting which heat seals together in a reliable manner, such as polyethylene or poly(ethyl-methyl acrylate) also known as EMA. Additionally, poly(ethylene-vinyl acetate) (EVA) or equivalent material may be used.
The probe sheaths of the prior art perform adequately to provide a sealed sheath around oral or anal thermometers in normal circumstances. However, in the rare but unfortunate circumstances where an accident or an unruly patient breaks the thermometer during use, the probe sheaths of the prior art are sometimes of insufficient strength to avoid rupturing. This can of course cause shards of thermometer and sometimes mercury to pass into the patient. Additionally, the major purpose of the probe sheath may then fail, that is, the protection of the patient from bacterial or viral exposure from an incompletely sterilized thermometer or other probe. Particularly in the case of small children or certain disabled patients, the patients may bite through the probe sheaths of the prior art while the thermometer or other probes are inserted in the mouth, resulting in possible viral or bacterial exposure to the patient.
In accordance with this invention, an improved probe sheath is provided in which the sheath is of a strength which is capable of substantially preventing bite-through in the mouth when enclosing a glass thermometer or other probe.
While other plastic materials are known to be stronger than polyethylene, EMA, or EVA, they also tend to be stiffer. For example, biaxially oriented poly(ethylene terephthalate) or polypropylene are very strong materials, but they are relatively stiff. Thus, a flat sheath made of such strong, stiff plastic materials can be very uncomfortable in the mouth, if such flat materials penetrate a significant distance under the tongue. There, their stiff, sharp edges can press into the delicate tissues beneath the tongue and cause discomfort. Also, while such materials are heat sealable with greater difficulty and more extreme conditions than plastics such as polyethylene, they can be reliably heat sealed in manufacturing processes to provide an independent, single layer sheath portion of a strong material which cannot be bitten through under normal circumstances.
In accordance with this invention, an improved probe sheath is provided which combines strength that is sufficient to substantially prevent bite-through in the human mouth, coupled with comfort when the sheath is inserted under the tongue. With such an increase in strength, the probe sheath is also much more reliable for protection against danger from breakage of a glass thermometer or the like being used, and also increased infection against bacterial or viral exposure is provided.